Display apparatus comprising diamond field emitters

Abstract

A novel and advantageous cathode structure for a field emission display apparatus is disclosed. A given pixel comprises a multiplicity of spaced apart emitter bodies on a support. A given emitter body comprises diamond and/or rare earth boride, and has a relatively sharp geometrical feature that facilitates electron emission from the emitter body. By way of example, the emitter body comprises diamond bodies grown on a support, or it comprises a pre-existing diamond particle that was placed on the support. Such emitter bodies generally can be provided easily and at low cost, and typically have naturally occurring sharp geometrical features such as points and edges. We have also discovered that appropriately grown rare earth boride films of thickness 30 nm or less may substantially improve electron emission from emitter bodies, and some preferred embodiments of the invention comprise a cathode structure that comprises a thin layer of, e.g., LaB 6 on the emitter bodies. Methods of making cathodes according to the invention are also disclosed.

We claim: 
     
       1. An article comprising field emission display means comprising a) a multi-pixel cathode, a given pixel having an area and comprising a multiplicity of spaced apart emitter bodies on a support;   b) an anode that is spaced apart from the cathode and comprises light emitting means;   c) a gate disposed between said anode and cathode; and   d) means for applying a voltage between said cathode and gate such that electrons are emitted from at least some of said emitter bodies and impinge on said light emitting means; CHARACTERIZED IN THAT     e) said support comprises first conductive material in contact with said emitter bodies of the given pixel;   f) the emitter bodies of the given pixel comprise in situ grown diamond-comprising islands disposed substantially randomly on said support, said diamond-comprising islands having substantially polyhedral shape, with relatively sharp geometrical features; and   g said diamond-comprising islands furthermore comprise second conductive material effective for facilitating electron emission from said diamond-comprising islands.   
     
     
       2. An article according to claim 1, wherein said second conductive material is doped diamond material. 
     
     
       3. An article according to claim 1, wherein said second conductive material comprises a rare earth boride. 
     
     
       4. An article according to claim 3, wherein the rare earth boride is a layer that is at most 30 nm thick. 
     
     
       5. An article according to claim 3, wherein the rare earth boride is selected from the group consisting of the La-borides and the Y-borides. 
     
     
       6. An article according to claim 1, wherein said diamond-comprising islands cover at most 50% of the area of the given pixel. 
     
     
       7. An article according to claim 1, wherein the relatively sharp geometrical features of the diamond-comprising islands are naturally occurring relatively sharp features. 
     
     
       8. An article according to claim 1, wherein the first conductive material is a metal or is a material that has a resistivity in the range 10 6  -10 9  Ω·cm. 
     
     
       9. An article according to claim 8 wherein the first conductive material comprises material that has resistivity in the range 10 6  -10 9  Ω·cm and is disposed on a conductive layer that is spaced apart from the diamond-comprising islands and is selected to facilitate applying said voltage by capacitative coupling. 
     
     
       10. An article comprising field emission display means comprising: a) a multi-pixel cathode, a given pixel having an area and comprising a multiplicity of spaced apart emitter bodies on a support;   b) an anode that is spaced apart from the cathode and comprises light emitting means;   c) a gate disposed between said anode and cathode; and   d) means for applying a voltage between said cathode and gate such that electrons are emitted from at least some of said emitter bodies and impinge on said light emitting means; CHARACTERIZED IN THAT     e) the emitter bodies of the given pixel are substantially randomly positioned on the support and comprise diamond, a given emitter body having relatively sharp features effective for facilitating electron emission from the emitter body;   f) said gate comprises a patterned metal layer disposed on insulating material that partially encloses said given emitter body, with a portion of said emitter body protruding from said insulating material, the protruding portion being spaced from the patterned metal layer and disposed within an aperture in the patterned metal layer, with the given emitter body being the only emitter body having a protruding portion within the given aperture.   
     
     
       11. Article according to claim 10, wherein the given emitter body comprises pre-existing diamond. 
     
     
       12. Article according to claim 10, wherein the insulating material is material of the type that forms a substantially conformal layer. 
     
     
       13. Article according to claim 10, wherein the given emitter body is an in situ grown diamond-comprising island disposed on the support.